Stressed plastic valve for laboratory glassware



Oct. 28, 1969 E. o. PHILLIPS 3,475,002

STRESSED PLASTIC VALVE FOR LABdRATORY GLASSWARE Original Filed March 9, 1965 V 4 Sheets-Sheet 1 EDwm D. PHILLIPS BYM WA/ ATTORNEYS Oct. 28, 1969 PHLUPS 3,475,002

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vulva-annual!!! United States Patent 3,475,002 STRESSED PLASTIC VALVE FOR LABORATORY GLASSWARE Edwin D. Phillips, 170 Albert St., North Plainfield, NJ. 07060 Original application Mar. 9, 1965, Ser. No. 446,763, now Patent No. 3,305,211, dated Feb. 21, 1967. Divided and this application Oct. 5, 1966, Ser. No. 604,085

Int. Cl. F16k 5/04, 5/18 U.S. Cl. 251-155 Clalms ABSTRACT OF THE DISCLOSURE The device is a stopcock to be employed in laboratory glassware wherein the glass barrel is of constant diameter. The stem or plug is formed of prestressed thermoplastic material such as Teflon with each end portion thereof sealed against longitudinal leakage of fluid between the barrel and plug by a plurality of peripheral ribs. The mid portion of the plug has grooves in its periphery providing communicating passageways between nipples on the barrel in certain positions of the plug.

This is a division of application Ser. No. 446,763, filed Mar. 9, 1965, and now Patent 3,305,211 and which, in turn, is a continuation-in-part of application Ser. No. 287,962, filed June 14, 1963, and now abandoned.

This invention relates generally to improvements in laboratory glassware and is directed particularly to improvements in valve structure for the same. I

In laboratory glassware the use of valves is extensively made for controlling the flow of fluids, either liquid or gaseous for the purpose of regulating the quantity of such fluid passing through apparatus or through tubes leading from one piece of apparatus to another, or for diverting the flow of fluid to different fluid lines. In any case it is particularly important that the valves used be constructed in such a manner as to maintain a complete fluid tight condition when closed or partially closed. By this it is meant that when the valve is completely closed it must be so tight as to prevent leakage of fluid, gaseous or liquid, from one side to the other and under all conditions the rotary portion of the valve must fit in the barrel with such a degree of tightness as to prevent fluid leakage along the length of the barrel to the ends thereof. On the other hand, the degree of tightness of the plug in the barrel of the valve must not be such as to make the operation of the valve diflicult.

Present laboratory all-glass valves are made by grinding a taper into a glass sleeve or barrel and then lapping in a glass valve stem or plug to fit securely in the sleeve. A spring clip is then used on the smaller end of the stem or plug to draw the latter firmly onto the seat. Such valve habitually become tight, upon being turned, to a point where it is difiicult to open and close the valve and accordingly the use of a suitable lubricant is required. This is not entirely satisfactory, since the lubricant frequently gets onto the hands of the operator and thus on the glassware.

Valves have been made wherein the stem or plug is formed of a synthetic resin, of the fluoro-carbon type, such as tetrafluoroethylene, and the copolymer of tetrafluoroethylene and fluorinated ethylene propylene, known in the trade as Teflon, the plug being made with a taper as in the glass valve plug. Such plastic stem or plug valves are not entirely satisfactory due to the fact that they are expensive to make due to the labor involved in making the taper of the stem, or plug, and of the sleeve to accurately match. Accordingly, such valves leak and if they may be made sufficiently tight initially, they will leak after a period of use and after being drawn onto the barrel seat, due to cold flow of the plastic material.

In view of the foregoing the present invention has for a principle object to provide a laboratory glassware valve embodying a thermoplastic rotary stem or plug and glass sleeve, designed in a novel manner whereby a tight leakproof engagement will be maintained at all times between the contacting or opposing surfaces of the plastic stem, or plug, and the glass sleeve or barrel.

A further object of the invention is to provide a valve structure of the character stated, wherein the thermoplastic stem is designed in such a manner as to utilize the cold flow characteristic of the plastic under stress to form, maintain, and ensure a tight fit between the parts and thus secure the desired seal.

Another object of the invention is to provide a valve structure embodying a sleeve or barrel or straight cylindrical bore, and a thermoplastic stem or plug of straight externally cylindrically form and wherein means is pro vided for effecting a prestressing of the valve stem or plug in the barrel to cause cold flow of the plastic material whereby it will exert the necessary pressure against the wall of the sleeve or barrel to form a tight leakproof seal.

Still another object of the invention is to provide an improved valve construction wherein the stem or plug is formed in a novel manner to facilitate gradual reduc- Lion of flow through the barrel between two or more pipe nes.

A still further object of the invention is to provide a burette type of valve or stopcock having a novel drip tip at the bottom end of the plug and formed of a thermoplastic resin, such as Teflon, threaded into a stem of the same material and functioning to expand or increase the outside diameter of the stem to effect and maintain a tight leakproof connection between the stem and the opposing wall of the encasing barrel or sleeve.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawings, wherein:

FIG. 1 is a view partly in longitudinal section and partly in elevation of a valve constructed in accordance with one embodiment of the present invention.

FIG. 2 is a longitudinal section taken substantially on the line 2-2 of FIG. 1.

FIG. 3 is a transverse section taken on the line 33 of FIG. 1.

FIG. 4 illustrates, partly in longitudinal section and partly in side elevation, a take-off valve or stopcock and flask stopper, constructed in accordance with the present lnventlon.

FIG. 5 is a longitudinal section taken substantially on the line 55 of FIG. 4.

FIG. 6 is a transverse section taken substantially on the line 66 of FIG. 4.

FIG. 7 illustrates another construction embodying an expansion plug threaded into the hollow stern for expanding the stem, the plug having a circumferential passage for through flow of fluid between opposite nipples.

FIG. 8 is a transverse section taken substantially on the line 8-8 of FIG. 7.

FIG. 9 is a longitudinal section taken substantially on the line 99 of FIG. 7.

FIG. 10 is a longitudinal section through a construction similar to FIG. 7 but illustrating another form of expansion plug.

FIG. 11 is a transverse section taken substantially on the line 1111 of FIG. 10.

FIG. 12 is a view partly in longitudinal section and partly in elevation of a burette valve or stopcock having an outlet through the bottom of the plug and illustrating a spiral flow channel in the surface of the plug.

FIG. 13 is a longitudinal section taken substantially on the line 1313 of FIG. 12.

FIG. 14 is a transverse section taken substantially on the line 1414 of FIG. 12.

FIG. 15 illustrates a modified form of expansion plug in the valve stem, in which the expansion plug carries spaced sealing rings.

FIG. 16 illustrates another construction, the valve stem being an elevation and the sleeve being in longitudinal section and showing another design of flow passage in the surface of the stem.

FIG. 17 is a transverse section taken substantially on the line 1717 of FIG. 16.

FIG. 18 illustrates a construction and longitudinal section, similar to FIG. 16 but showing a three-way flow arrangement.

FIG. 19 is a longitudinal section on line 19-19 of FIG. 18 illustrating the construction of FIG. 18 and showing the three-way nipples on the valve sleeve or barrel.

FIG. 20 illustrates the lower portion of a burette and valve construction, in which the valve stem is shown in elevation.

FIG. 21 illustrates another embodiment of the invention utilizing compressible granular material with a compression plug in a hollow stem for effecting lateral compression of the stem in the sleeve.

FIG. 22 is a detail view on an enlarged scale of a longitudinally sectioned sleeve with a thermoplastic plug stem therein and illustrating the circumferential grooving of the stem at opposite sides of the flow channel and also illustrating a locking beading arrangement between the stem body and the barrel or sleeve body.

Referring now more particularly to the drawings, it will be seen that the valve or stopcock construction of the present invention in each of the illustrated embodiments thereof, comprises a barrel or sleeve of straight cylindrical form and generally designated B, into which is inserted a stem or plug, generally designated S, which is also of straight cylindrical form and has at one end an integral head H. These general reference characters will be used throughout for the different embodiments of the valve together with individual reference numerals for specific parts of the valve structure of each embodiment.

Preferably the barrel or sleeve B is formed of glass. This barrel, as above stated, has a straight bore which is of constant diameter throughout the length thereof 01' throughout that portion of its length with which the exterior of the' stem S is in contact. That is, the bore, designated in each embodiment is as nearly constant in diameter throughout its length as is possible to make the same. However, slight variations in the diameter or any inequalities in the circularity of the interior of the bore, if such occurs, will have no effect upon the tightness of the valve as the fit of the stem or plug in the sleeve is such as to avoid any leakage. In other words, the stem of the valve conforms itself to irregularities in the cylinder surface so that if the cylinder should be slightly out-ofround, this will not affect the tightness of the fit of the stem in the barrel.

The stem S in each instance is formed throughout with the head thereof, of the plastic Teflon.

At the head end of the stem in each of the embodiments of FIGS. 1 to 22, a collar 12 is formed which is of larger diameter than the body portion of the stem and bears against one end of the barrel or sleeve when the stem is in operative position therein, as illustrated in the several figures referred to.

As will be hereinafter specifically described, the stem S in each embodiment is provided ubstantially midway between its ends and in its surface with means for conducting fluid transversely of the valve structure.

The novel tight leakproof engagement between the interior surface of the barrel or the surface of the bore of the barrel and the exterior surface of the stem, is effected in accordance with the present invention by the novel prestressing of the thermoplastic material in the barrel or sleeve whereby cold flow of the plastic will force the body of the stem outwardly and tightly against the surface of the bore of the sleeve. Such prestressing of the stem is transversely of or normal to the axis of the stem and sleeve wall or parallel to the wall.

A particular advantage of the present invention, in forming the barrel and stem straight, throughout, resides in the fact that no tapering of the cooperating surfaces of the parts is required, and consequently, in addition to the fact that no grinding and lapping-in is called for, there is no requirement that spring clips be used or that nuts be threaded on the ends of the stems, to draw or pull the stem longitudinally into tight engagement with its seat.

Each of the Teflon stems, after being turned or shaped to the proper outside diameter, has formed therein and therearound, in a portion thereof on each side of the centrally located flow passages, a multiplicity of relatively fine encircling grooves 14, thereby forming the fine circular ribs 14a.

In certain of the stems as hereinafter set forth, the portions of the stem in which these ribs are formed, are made slightly oversize with respect to the diameter of the bore of the barrel or sleeve in which they are formed. This oversize is approximately of an inch. The grooves are spaced about to of an inch apart and approximately 10 or 12 of the ribs are thus formed in each of the portions of the stem. The depth of each groove may also be approximately the same as the spacing apart of the grooves or a slightly larger spacing between the grooves may be used.

The ribs 14a when made oversize as stated will permit the valve stem to be forced into the barrel or sleeve and in being so forced into the sleeve, the ribs will be compressed land will thus form a tight seal with the surface of the ore.

In the central area of the stem, between the two groups of ribs, the stem may be made of approximately the the same diameter as the barrel bore and thus will not offer any resistance to the forcing of the stem into the bore. The ribs preferably extend all the way to the ends of the sleeve.

A straight cylindrical stem such as that employed in the valves of this invention, if made of a diameter to obtain a slight press fit, to avoid leakage, is almost impossible to insert into a barrel, because of the length of the stem, and is much too diflicult to turn because the applied stress is too high. By the provision of the fine grooves in the body of the stem and in relatively large number at opposite sides of the central portion in which the flow passages are formed, only the top of the ribs receive interference or resistance and because of the narrowness of the ribs, they will be compressed, or precompressed, when the stem is forced into the barrel and will then react to impose a film pressure against the bore of the valve and form a tight seal.

The valve stems in the embodiments shown in FIGS. 1 to 22, to which embodiments the following description is particularly directed, up to and including FIG. 22, are hollow or tubular and the hollow centers are open at the end of the barrel opposite from the head and in some instances, as shown in certain of the embodiments hereinafter to be described, means is provided within the hollow stem for exerting an expansive pressure to force the ribs of the stem against the surface of the sleeve bore. In these embodiments, while the ribs may be formed oversize, if desired, this is not absolutely necessary in order to obtain a tight seal since the imposition of outward pressure from within the stem wil bring about the desired result.

In FIGS. 1 to 3, the valve barrel is illustrated as being formed with the oppositely located nipples 16. The barrel and nipples are shown as being formed of glass and the nipples are fused to the body 18, in the conventional manner, opening into the bore by way of the reduced neck portion 20.

The nipples 16 are shown offset one from the other in the longitudinal direction of the barrel, however, they may be suitably bent to bring the outer end portions in alignment while the apertured throats 20 at the inner ends are in the offset position shown.

The stem here shown is hollow from the end remote from the head to the opposite end near the collar 12. This hollow form contributes to some extent to the required compressibility of the stem, although the actual sealing effect results from the deformation of the ribs as the stem is forced into the undersize bore 10 of the barrel or sleeve.

The body portion 22 of the stem if formed in the outer surface thereof with a novel flow channel configuration by means of which a rate of flow of fluid from one nipple to the other may he graduated from a full flow down to a very slow flow just prior to the complete shutting off of the flow entirely. In this flow channel arrangement there is provided the annular channel 24- which encircles the body 22 and is in the plane of one of the openings 20, here shown as the opening for the uppermost nipple 16. This channel communicates with the short longitudially extending channel 26 which, in turn, communicates with the spiral or incompletely circular channel 28 which is in the plane of the other nipple opening 20. This incompletely circular channel is shown as having an area of major width, see FIG. 2, which tapers off toward the opposite ends of the channel to zero width as indicated at 30. Thus it will be seen that by rotating the stem to a position where the major width portion of the channel 28 registers with the adjacent neck opening 20, full flow of fluid may be realized from one nipple to the other and when the flow is to be reduced, this is effected by rotating the stem in either direction to bring the gradually narrowing portion of the channel around with respect to the adjacent opening 20 and if the flow is to be fully shut off, then the non-channeled portion 32 intervening between the ends of the channel 28 is brought into position to cover the adjacent opening 20, as will be readily apparent, particularly upon reference to FIG. 3.

While the channel 28 has been illustrated in FIG. 2 as having its maximum width in between the two ends thereof, it may be formed to have its maximum width extend from one end of the channel around to the opposite end and to be gradually reduced in width from the wider end to the opposite end of zero width.

FIG. 4 illustrates a valve structure combined with a flask stopper. In this embodiment the body 34 of the barrel is formed at one end integral with the tubular ground glass flask stopper 36. A single nipple 38 is joined to the barrel body and communicates with the bore 10 thereof through the neck opening 40.

In this embodiment the body 42 of the stem is provided in its outer surface with the encircling flow channel 44 and with the short longitudinal extension thereof as indicated at 46, which extension is adapted to communicate at its lower end with the opening 40.

The stem of this embodiment is hollow as shown, so that the open lower end thereof may communicate through the stopper 36 with a flask and the hollow interior 48 of the stem communicates with the circular flow channel 44 by way of the radial bore 50.

FIGS. 7, 8, and 9 illustrate an embodiment of the valve structure employing a means for prestressing the Teflon valve stem parallel to the valve wall or to the axis of the stem. In this construction the body 52 of the barrel B is shown as having the opposite nipples 54in communication with the interior or bore of the valve barrel and the stem has the body 56 thereof formed with the opposite radial apertures 58 which open through the wall of the stern into the hollow interior thereof.

The hollow interior of the body 56 forms a chamber 60 which is slightly tapered from the open end of the chamber as shown in FIG. 9, and the chamber at its outer end is screw threaded as indicated at 62.

The numeral 64 designates a tapered expansion plug which is adapted for extension into the tapered chamber 60 and this plug at its outer end is screw threaded as indicated at 66 for threaded engagement with the larger outer end of the chamber whereby upon threading the expansion plug inwardly, this effects a prestressing axially along the screw which by the eifect of cold flow will force the body 56 outwardly tightly against the wall or surface of the bore 10 of the barrel.

The surface of the expansion plug 64 is provided with the circumferential flow channel 68 located in a transverse plane for communication with or register with the radial apertures 58.

FIGS. 10 and 11 illustrate the same construction in the valve barrel and in the body of the stern as is shown in the adjacent FIG. 9. However, the expansion plug of this embodiment, designated 7 0', is provided with the transverse through passage 72 as shown in FIG. 11, which passage, while it may be of any suitable form or configuration, is here illustrated as being narrower between its ends than at the opposite ends or, in other words, it is illustrated as having a substantially hour-glass form.

FIGS. 12 to 14 inclusive, illustrate the application of the present invention to a burette stop-cock of the type having an outlet through the bottom of the stopcock plug and combined with the means for prestressing parallel to the axis of the stern for acquiring a tight leakproof engagement between the stem and the bore of the barrel.

In this embodiment of the invention the body of the barrel B is generally designated 74 while the body of the stem S is generally designated 76.

The body 74 has a single nipple 78 joined to and opening into the bore 10 of the barrel body, while the body 76 of the stem has the tapered chamber 78 therein which is open at the end remote from the head H and the chamber at its outer and larger end is screw threaded as indicated at 80'.

The numeral 82 designates a drip tip having the externally threaded circular body portion 84 for threaded engagement in the end of the chamber 78 and having the externally tapered tip portion 86. A flow passage 88 is formed axially through the tip 82.

The exterior surface of the body 76 is shown as having the incomplete circular flow passage 90 formed therein and communicating by way of the radial aperture 92 with the chamber 78. This flow passage 90 is preferably of gradually decreasing width from a maximum width at one end to a zero width at 94, at its other end, and it is located in a transverse plane of the body 76 for register with the end of the nipple, as shown. With this construction it will be seen that there is provided a valve or stopcock for supplying fluid in drop amounts from a burette or other apparatus, with means for controlling the drop flow.

FIG. 15 illustrates a valve structure wherein the expansion plug is provided with a transverse, through flow passage and with sealing rings on opposite sides of the passage. This construction provides additional sealing where such may be considered necessary.

In the construction of FIG. 15, the body of the stem is designated 96 and the tapered plug which is inserted in the tapered bore 98 in the body 96, is designated 100. This construction, it will be seen, is up to this point the same as the construction shown in FIGS. 9 and 10.

The plug 100 has a transverse or radial flow passage 102 which is designed, upon rotation of the stem, to align with ends of nipples, not illustrated, joined to the body 104 of the barrel. Such a nipple arrangement would be like that illustrated in FIGS. 7 and 8. An end of one such nipple is designated by the dotted line circle 106.

The expansion plug 100 is provided on opposite sides of the radial passage 102, with ring grooves 108, in each of which is positioned a gasket ring which has tight engagement with the surface of the tapered bore 98 and when the expansion plug 100 is threaded inwardly it will be apparent that the hereinbefore described prestressing of the latter in the longitudinal direction thereof will also effect the compression of the rings 110.

FIGS. 16 and 17 illustrate an embodiment of the valve in which the body of the stem is provided with an encircling or girdling flow passage which communicates with two oppositely located longitudinal branches positioned to be brought into communication or register at their closed ends, simultaneously with opposite nipple openings.

In this construction the body of the barrel is generally designated 112 while the body of the stem is designated 114. Here also the circumferentially grooved portions are formed oversize so that the sealing ribs 14 will establish a firm or tight leakproof engagement with the surface of the bore in the barrel body.

The barrel body is illustrated as having joined thereto the opposite nipples 116 which open into the bore in the illustrated manner.

The body 114 of the stem is provided with an encircling or girdling flow channel 118 which is removed axially of the stem from the aligned ends of the nipples 16. At diametrically opposite locations the surface of the body 114 is provided with the short longitudinally extending flow channels 120, each of which opens at one end into the circumferential channel 118, while the opposite or closed or blind end of each of the short channels 120 is located in the plane, transversely of the stem, of the adjacent ends of the nipples 116.

With this arrangement it will be seen that both of the axial channels 120 may be brought into registry simultaneously with the nipples so that fluid may flow from one thereof into the circumferential channel 118 from which it will then flow to the opposite nipple by way of the other axial channel 120. This construction provides for a quicker shut off of fluid flow than may be had with a straight through radial passage.

FIG. 19 illustrates the application of the invention to a multi-way valve structure.

In this figure the body of the barrel B is designated 122 while the body of the stem S is designated 124.

As shown, the barrel has joined thereto, the three nipples 126, 128 and 130. The nipples 128 and 130' are spaced apart in the longitudinal direction of the barrel, while the nipple 126 is aligned transversely of the barrel with the nipple 130.

The stem has formed circumferentially in the surface thereof, the flow channel 132 which is in the plane transversely of the barrel and stem of the nipple 128 so as to be at all times in communication with this nipple.

Selective transfer of fluid between the nipple 128 and the nipples 126 and 130 is effected by means of the single longitudinally extending short flow channel 134 formed in the surface of the stem and communicating at one end with the circumferential channel 132. The opposite or blind end of the channel 134 is in a plane transversely of the stem with the aligned nipples 126 and 130. Accordingly it will be seen that upon rotation of the stem, the blind end of the channel 134 may be brought into register with either the nipple 126 or the nipple 130. With this arrangement, communication may be established between the nipples 126 and 128 or between the nipples 128 and 130. It will also be apparent, of course, that additional nipples may be joined to the barrel body 122 and which additional nipples may be put in communication with the nipple 128.

FIG. 20 illustrates another embodiment of the valve structure, shown in association with a burette, the lower portion only of which is illustrated, and which is generally designated 136. The body 138 of the barrel B is disposed transversely of the longitudinal axis of the burette and is in communication with the outlet end of the burette through the neck aperture 140. Diametrically opposite from the body of the burette and aligned with the neck aperture 140, is the short discharge tip or nipple 142 having the neck opening 144 which is aligned with the opening 140.

In this valve construction the hollow stem body 146 of the stem is shown in association with an expansion plug 148 threaded therein to function in the same manner as the hereinbefore described expansion plugs and this expansion plug is shown as having a through radial passage 150 which is aligned with openings 152 formed in opposite sides and through the wall of the stem. Thus it will be seen that when the stem is rotated to one position fluid may be discharged from the burette to and from the tip 142, or it may be shut ofl? by rotating the plug from the position illustrated.

FIG. 21 illustrates another method of applying preslure to the stem body for prestressing in a direction normal to the axis of the stem and housing. In this figure the body of the cylinder is designated 154 while the body of the stem S is designated 156 and the chamber formed axially in the stem, is designated 158.

Two nipples 160 are shown joined to the body 154 of the barrel for fluid connection with a flow passage or channel 162. This flow channel is shown as being incompletely circular whereby an unchanneled portion between the ends of the channel may be brought into position to close an aperture leading to one of the nipples 160 as will be readily apparent.

In this latter construction the chamber 158 of the stem is filled with granular neoprene rubber or silicone rubber 164, and there is threaded in the open end of the chamber, a compression plug 166. Thus it will be seen that when the plug 166 is threaded inwardly, pressure will be applied to the granular rubber material 164 which will produce side pressures on the valve stem body to thus ensure a tight leakproof engagement between the ribs on the stem and the surface of the bore of the barrel in which the stem is located.

FIG. 22 illustrates one of the valve structures on an enlarged scale with the barrel being in longitudinal section and the stern in elevation. This enlarged illustration shows details embodied in all of the different forms of the valves hereinbefore described, and while the stem structure is the same as that illustrated in FIG. 16, and the barrel body is shown with the two opposite nipples 116 of the structure of FIG. 16, it is to be understood that any of the other stem constructions or barrel constructions may be and preferably are formed with the details about to be described. The same reference numerals, accordingly, will be applied here as are used in the structure shown in FIG. 16.

Each of the stem bodies is formed at the upper end thereof with the encircling groove 168 which is immediately below the collar portion 12 of the stem. This groove receives the very small or low bead 170 formed around the top inside edge of the body 112 of the barrel. At the opposite end of the barrel body from the bead 170, the inside edge of the barrel bore is formed with the rib 172. This is positioned to be contacted by the adjacent end of the stem body as shown. Thus the bead 170 engaging in the groove 168 establishes a locking coupling between the parts.

As hereinbefore stated, laboratory glassware valves constructed in accordance with the present invention in its different disclosed embodiments, have many advantages over valves heretofore produced where tapered plugs or stems are employed. As an example, Teflon material can be easily machined to the desired cylindrical form and grooves as stated to establish the tight leakproof connection with the enclosing barrel or sleeve. It does not have to be ground for a taper as is required in other valve structures.

Another feature of advantage is that with valves constructed in accordance with the present invention the stems are readily interchangeable and even though there may be slight variations in the circularity of the bores of the valves or sleeves of the different valves, the stems will form the desired leakproof engagement with the barrel bore. Ordinary laboratory tubing, such as would be used for forming the barrel or sleeve of the present valve may deviate from an accurateor true concentricity, as much as of an inch. In such case the formation of the cylindrical stem oversize in the amount hereinbefore stated will cause the stem to conform to the slight concentricity deviation and still maintain a leakproof connection.

In conventional tapered plug or tapered stem valves, the stem is ground to fit one sleeve only and accordingly another sleeve, or a sleeve of another valve, if not of exactly the same taper, will not receive the stem since the larger end of the stem or plug would prevent its completeientry and seating. No difliculty such as this occurs in connection with valves of the present invention.

From the foregoingvit will: be apparent that there is provided by the present invention a new and novel laboratory valve structure which has new and unexpected results and advantages over other types of valves.

I claim:

1. A valve comprising a glass barrel having a straight cylindrical bore therethrough, a tubular nipple joined at one end to the side of the barrel, means forming a communication between said end of the nipple and the interior of the barrel, a straight cylindrical plug extending into the barrel through one end of the latter and snugly rotatably and peripherally engaging the surface of the bore, flow channel forming means in said cylindrical plug and adapted to register with the said communication forming means, tubular means joined to said barrel and having an end connected with said flow channel forming means, said flow channel extending in part longitudinally through the plug and opening through one end thereof, said plug being formed of Teflon, and means for utilizing the cold flow characteristic of the Teflon material to establish a fluid tight compression of the surface of the plug against the surface of the barrel bore.

2. A valve comprising a length of glass tubing open at its ends and forming a rotary plug barrel, said tubing having a straight cylindrical bore of substantially constant diameter from end to end, plural tubular means joined to said barrel and opening thereinto, a cylindrical thermoplastic plug of substantially constant overall diameter fitting in and in direct contact with said bore for rotation therein, means facilitating axial rotation of said plug, flow channel forming means in said plug adapted upon rotation for establishing and interrupting communication between said plural tubular means, and means effecting transverse pressure between the plug and the opposing surface of said bore upon opposite sides of the opening into the barrel of one of said tubular means, for forming a leakproof engagement between said opposing surfaces, said plug having an axial chamber therein opening through the end thereof opposite from the said means for facilitating rotation of the plug and said means for effecting transverse pressure consisting of a material within said bore and under a compressive force exerted in the axial direction of the bore.

3. The invention according to claim 2, wherein said plug has an axially directed chamber extending throughout the major portion of the length thereof and opening through the end of the plug opposite from the said means facilitating rotation of the plug, the said bore being tapered from its open end, and wherein the said means for eflecting transverse pressure consists of a tapered compression plug extending into said tapered bore and having threaded connection with the surface of the bore.

4. In laboratory glassware, a valve comprising a glass barrel having a straight cylindrical bore therethrough, a tubular nipple joined at one end to the side of the barrel, means forming a communication between said end of the nipple and the interior of the barrel, said bore being of substantially contsant diameter throughout, a straight cylindrical plug extending into the bore of the barrel through one end of the latter, said plug being of substantially constant overall diameter throughout the portion thereof positioned in the barrel and having snug rotational engagement with the surface of the bore, flow channel forming means in said cylindrical plug having one end adapted to registerwith said communication forming means upon a predetermined rotation of the plug in the barrel, tubular means joined to said barrel and having an end connected with said flow channel forming means, said plug being formed of Teflon, means for utilizing the cold flow characteristic of the Teflon material to establish a fluid tight compression of the sur face of the plug against the surface of the barrel core, and said flow channel forming means including as a part thereof, a portion formed in and extending at least in part circumferentially of the surface of the plug, the said fluid tight compression of the surface of the plug against the surface of the valve 'core being located at opposite sides of the said communication forming means, in the longitudinal direction of the plug.

5. The invention according to claim 4, wherein the said circumferentially extending portion of the channel forming means has a part of maxim-um width and tapers to an end part of zero width whereby the rate of flow of fluid may be progressively reduced to a minimum prior to complete shut-off.

'6. In laboratory glassware, a valve comprising a length of glass tubing forming a valve plug barrel and having a bore of substantially constant diameter throughout and open at its ends, a pair of tubular nipples each joined at an end to the barrel and opening through an aperture into said barrel bore, a valve plug of Teflon in said bore and having an overall diameter permitting its full insertion into the bore, the plug being insertable into the bore from either end of the latter, the plug having a head on one end, a fluid flow channel in the surface of the plug, said channel including a portion fully encircling the plug and in register with an aperture of one nipple and a second portion only partially encircling the plug and adapted to register with the aperture of the other nipple and a third portion connecting said first and second portions, the plug surface in the part thereof lying between the ends of said partially encircling portion closing the said aperture of said other nipple in one position of rotation of the plug, and means for forming a tight leakproof engagement between the plug and the surface of the bore at opposite sides of the apertures.

7. The invention according to claim 6, wherein the said second portion of said channel tapers at one'end to zero width.

8. The invention according to claim 7, wherein the last stated means comprises a multiplicity of relative fine ribs of the plug material and encircling the plug at each of the two opposite sides of the first mentioned and second mentioned portions of the flow channel, and said ribs having an overall diameter slightly greater than the barrel whereby they become deformed upon insertion of the plug into the barrel bore.

9. A valve comprising a glass barrel having a straight cylindrical bore therethrough, a tubular nipple jointed at one end to the side of the barrel, means forming a communication between said end of the nipple and the interior of the barrel, a straight cylindrical plug extending into the barrel through one end of the latter and snugly, rotatably and peripherally engaging the surface of the bore, flow channel forming means in the surface of the plug and partially encircling the plug and positioned to register with said communication forming means, said plug being hollow and open at one end and said flow channel forming means being continued through the wall of the plug to the hollow interior thereof, a drip tip having a body portion inserted into the said open end of the plug and secured to the plug and having a tip portion of substantial length and tapering to a relatively small free end, said drip tip having a bore axially therethrough and opening into the interior of the plug, the plug and drip tip being formed of Teflon, and means for forming a tight leakproof engagement between the surface of the plug and the surface of the bore on opposite sides of said flow channel forming means, said hollow interior of the plug is tapered from the open end and wherein the said body of said drip tip is secured in said open end by screw threads and functions upon inwardly threading movement to radially compress the outer surface of the plug against said bore.

10. The invention according to claim 9, wherein the said means for establishing the said fluid tight engagement between the plug and the bore consists of a multiplicity of relatively fine ribs formed around the plug n opposite sides of the flow channel forming means and said ribs being of an overall diameter greater than the diameter of said bore whereby the ribs are deformed upon forcible insertion of the plug into the bore.

References Cited UNITED STATES PATENTS 1,024,908 4/1912 Powelsen 25 13 11 XR 2,854,027 9/1958 Kaiser et al. 251-310 XR 3,012,752 12/1961 Buck 251-309 3,185,179 5/1965 Harautuneian 251181 XR 3,224,461 12/ 1965 Kurek 251-2l4 3,259,358 7/ 1966 Tripoli 251-214 3,325,143 6/ 1967 Phillips 251-311 FOREIGN PATENTS 1,133,818 11/1956 France.

Great Britain.

HENRY T. KLINKSIEK, Primary Examiner U.S. Cl. X.R. 

